Over 300 million tons of plastic are produced around the world every year. But only 10% of those plastics are recycled properly. The rest end up in landfills polluting our environment. So what do we do? Researchers in Spain think they might have the answer: a caterpillar with the ability to digest plastic.

How Were the Caterpillars Discovered?

Federica Bertocchini, a researcher for the Spanish National Research Council (CSIC), first discovered the tiny plastic eating caterpillars. She came upon them by accident; Bertocchini was removing caterpillars from her beehive and putting them into a plastic grocery bag.

The caterpillars Bertocchini found are known as waxworms. They are the larval stage of a common moth found in Europe, Asia, North America and Australia. They are often sold as food at pet stores and are known to infest beehives where they like to eat the beeswax.

After leaving the caterpillars in the plastic bag for a few hours, Bertocchini returned to find holes in the bag where the caterpillars had chewed their way out. At first, Bertocchini assumed the caterpillars were just chewing through the plastic but not actually eating it. However, upon further research in the lab, she learned that the caterpillars were actually ingesting the polyethylene plastic.

With further studying, Bertocchini and her team of researchers learned that the caterpillars began to produce holes in the film of polyethylene plastic within 45 minutes of making contact. They digested the polyethylene and turned it into ethylene glycol, a biodegradable compound. They learned that the caterpillars’ ability to digest plastic was linked to their ability to digest beeswax.  

Are the Worms Effective? Or Are They Too Effective?

While researchers proved that the waxworm caterpillar could digest plastic, it’s obvious that the waxworm has no huge desire to eat plastic. Waxworms are common around the globe; if they truly enjoyed eating plastic, we would have seen more mayhem from swarms of waxworms at garbage dumps or even on our plastic lawn furniture. For example, with Bertocchini’s plastic bag, the caterpillars ate enough plastic to escape the bag but didn’t stick around to eat more as a tasty meal.

In Bertocchini’s example, she placed approximately 100 caterpillars in a standard plastic grocery bag. After 12 hours, the caterpillars had eaten 92 mg of the bag - a miniscule amount considering the entire bag weighs 5.5 grams (5500 mg) or 1.67% of the entire bag. This means it would take 100 caterpillars almost 30 full days (717 hours) to eat an entire bag - clearly caterpillars are not incredibly effective at decomposing plastics.

But compared to the alternative, 20 to 1000 years to decompose a plastic bag to microscopic particles in the natural environment, the waxworms have it. Plus, the waxworms convert the plastic to biodegradable compounds instead of just breaking down the plastic.

Does the Solution To Our Trash Problem Lie in the Caterpillars?

While the waxworm caterpillars work better than the natural environment at breaking down plastics, they are probably not the answer to our trash problem. It would be unrealistic to release millions and millions of waxworms at garbage disposals and wait years for them to do their thing. However, the solution may lie within the worms themselves.

Researchers are looking at the chemistry inside the waxworms’ stomachs to see if there is a molecule responsible for degrading polyethylene plastic. If they could find that molecule, they could isolate it and reproduce it on a larger scale so it would have a greater impact in degrading plastics. Researchers are also looking at specific bacterias that live in the guts of waxworms and similar caterpillars to see if that is responsible for breaking down the plastic. So while the caterpillars themselves may not be the key, the solution to degrading plastics may lie inside of them.